Method of manufacturing plastic enclosures

ABSTRACT

A rigid plastic enclosure is made from flat blanks. The enclosure is particularly well suited for use as an electrical or electronic component enclosure. The top, bottom, back, and side walls of the enclosure are parts of a structure made by cutting and/or routing a sheet of plastic which can be folded into an open-faced, box-shaped structure. A cover or face plate can be fastened to the structure to complete the enclosure. Because the enclosure is constructed from plastic, holes can be easily drilled into its walls, eliminating the need for providing knockout holes at predetermined locations.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 08/251,741, filed May 27,1994, now U.S. Pat. No. 5,555,989 which is a continuation-in-part ofU.S. patent application Ser. No. 08/007,567, filed Jan. 22, 1993, nowU.S. Pat. No. 5,316,165 which is a continuation-in-part of U.S. patentapplication Ser. No. 07/683,783, filed Apr. 11, 1991, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to plastic enclosures which can be storedand shipped as flat sheets but are capable of being folded up alongflexible fold lines and locked together to make rigid boxlikeenclosures, and, more particularly, to such enclosures which aresuitable for use as wall-mounted electrical component enclosures, suchas pull boxes, junction boxes, splice boxes, and equipment cabinets.

DESCRIPTION OF RELATED ART

Electrical component enclosures, such as junction boxes, are commonlymade from sheet metal. Because fabrication of sheet metal enclosureswould be difficult and time-consuming if done on site by an end user,they are usually shipped preassembled, which means that shipping andstorage space must be wasted on the empty volume within the enclosure.

During both the initial installation of electrical components within theenclosure and during subsequent repair of these components, anelectrician's access to the electrical components is generally limitedto a single open panel at the front face or at one wall of theenclosure. This restricted access often makes it awkward and difficultto work on the electrical components in the enclosure, which results inmore time being expended on installation or repair than would otherwisebe required if the sidewalls were not in the way.

Because it is relatively difficult to cut or drill holes into metal, anelectrician is generally not completely free to run cable or conduitinto a sheet metal enclosure at whichever location he desires, but, tothe contrary, he is generally limited to standard size knockout holeswhich are provided at predetermined locations in the sidewalls of theenclosure. A further disadvantage of sheet metal enclosures is thatlarger enclosures can be difficult to mount on a wall because of theirweight.

Known molded plastic electrical component enclosures and customizedplastic enclosures which are solvent-cemented or glued together orheat-welded by hand are lighter, and can be cut or drilled more easilythan metal enclosures, but they still have the remaining disadvantagesof wasted shipping and storage space, limited access to componentscontained therein, and are relatively expensive.

Various methods of imparting fold lines to hard plastic materials areknown. U.S. Pat. Nos. 3,292,513; 3,334,802; 3,350,492; 3,594,464;3,768,950 4,373,929; 4,386,926; and 4,664,648; all disclose varioustechniques for cold-scoring plastic sheeting by means of mechanicaldeformation to create fold lines. Techniques for creating fold lineswhich involve a combination of heating to soften the plastic andmechanical deformation are disclosed in U.S. Pat. Nos. 3,379,814;3,589,022; 3,907,193; 4,179,252; 4,642,086; and 4,946,430. U.S. Pat.Nos. 3,132,649 and 3,201,145 teach plastic molding techniques forimparting fold lines. These patents are generally directed to methods ofproviding fold lines in plastic sheeting used for packaging consumergoods, wherein the plastic sheeting is capable of being handled by highspeed folding and filling machines. Foldable plastic containers producedby known techniques are generally not susceptible to reuse withoutsubstantial loss in utility, nor are they generally capable of beingeasily assembled without specially designed machinery and adhesiveagents, nor do they have sufficient mechanical strength forconstruction-related applications.

SUMMARY OF THE INVENTION

The invention provides durable plastic enclosures which can be shippedand stored flat to save space and which can be folded up along flexiblefold lines and provided with covers to make boxlike enclosures, thesidewalls of which can be partially unfolded so that they are insubstantially the same plane as the backplate to permit easy access toany components within the enclosure. The invention is particularlyuseful as an electrical or electronic component enclosure, and issuitable for both high voltage and low voltage applications.

The enclosure is made from plastic sheeting, and preferably from aplastic having high impact strength, with polyvinyl chloride beinggenerally preferred. The plastic sheeting is cut and grooved to form ablank with fold lines so that it can be folded into an open-faced,box-shaped structure. The foldable plastic blank has a backplate, foursidewalls with an edge of each sidewall attached to an edge of thebackplate via an integral fold line or hinge, and flanges with an edgeof each flange attached via an integral fold line to an edge of asidewall which is opposite to the edge of the sidewall attached to thebackplate. The sidewalls and flanges are foldable along the fold linesto form a six-sided structure. At each end of each flange is aprojection or a slot which respectively engages an interlocking slot orprojection on the end of an adjacent flange when in the folded position.The enclosure is completed, after the walls and flanges are folded andthe interlocking means at the ends of the flanges have been engaged, byaffixing a plastic faceplate to the flanges or otherwise closing theopen or accessible face with a faceplate.

The fold lines between the sidewalls and the backplate, and between theflanges and the sidewalls, are created by cutting or sawing grooves intothe plastic sheet to provide a narrow strip of reduced thickness at thebottom of the groove which can be easily bent to serve as a hinge. Thegrooves are predominately V-shaped with an included angle ofsubstantially 90 degrees, with one wall of the groove having a step-likelinear ridge and the opposing wall having a step-like linear furrow sothat when a sidewall is bent 90 degrees relative to the backplate, thestep-like ridge fits into the step-like furrow to provide four contactsurfaces at each folded hinge, thereby enhancing the structuralstability of the enclosure.

The two unattached edges of each sidewall are beveled to provide afitted non-overlapping corner when the sidewalls are folded to theassembled position. At each edge of the assembled enclosure where onesidewall intersects with another, one beveled edge is preferablyprovided with a step-like ridge as described above and the otherabutting beveled edge is provided with a step-like furrow. These ridgeand furrow features of the beveled edges of the sidewalls arestructurally identical to the ridge and furrow features of the "V"grooves.

The present invention provides an economical alternative to enclosurescurrently used by electricians for housing electrical equipment. Becausethe enclosure is made from a low conductivity or non-conductive plasticmaterial, there is a reduced risk of electrical shock with the inventionas compared to standard sheet metal enclosures. Additionally, theinvention is lighter, easier to install, easier to work with, andrequires less space for storage and shipment than electrical enclosureswhich were previously used.

In accordance with another aspect of the invention, protection againstelectromagnetic interference and static electricity buildup is providedby incorporating a static-dissipative additive directly into thepolymeric blend from which the plastic sheeting is made or astatic-dissipative layer in the plastic sheet. Goods such as printedcircuit boards, which require protection against electromagneticinterference and electrostatic buildup, are shipped in enclosures madefrom such plastic sheets. At the termination point of the shipment, thegoods are removed from the enclosure, the enclosure is disassembled andfolded flat and then shipped back to the starting point for reuse.

It is also possible to form a strong, easy to use and economicalenclosure from a pair of foldable blanks. The blanks are cut from one ormore plastic sheets. Each blank has a pair of grooves cut in its surfaceto provide live hinge fold lines. The blanks are folded into three-sidedstructures that are interfit to form a box-like enclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will becomeapparent upon consideration of the detailed description of the presentlypreferred embodiment when taken in conjunction with the accompanyingdrawings.

FIG. 1 is a top plan view of the plastic blank after the perimeter cut;

FIG. 2 is a top plan view of the blank of FIG. 1 after the parallel "V"grooves for the fold lines have been cut out;

FIG. 3 is a top plan view of the blank of FIG. 2 after the cornerportions have been cut out and holes drilled;

FIG. 4 is a top plan view of the cover for the structure folded up fromthe blank of FIG. 3;

FIG. 5 is an enlarged, fragmentary, cross-sectional view of theperimeter router for cutting out the blank of FIG. 1;

FIG. 6 is an enlarged, fragmentary, cross-sectional view of the circularsaw blade used to cut out the parallel "V" grooves in the blank of FIG.2;

FIG. 7 is an enlarged, fragmentary, cross-sectional view of the routerused to cut the corner portions off from the blank of FIG. 2;

FIG. 8 is an enlarged, fragmentary, cross-sectional view of the foldableplastic blank taken substantially along line 8--8 in FIG. 3;

FIG. 9 is an enlarged, fragmentary, cross-sectional view of the foldableplastic blank of FIG. 3, showing a flexible hinge in the folded-upposition;

FIG. 10 is an enlarged, fragmentary, cross-sectional view, showing acorner with adjoining sidewall edges in the assembled condition;

FIG. 11 is a fragmentary top view of the flanged frame of a foldedenclosure, showing the interlocking projection and slot as assembled;

FIG. 12 is an enlarged, fragmentary, cross-sectional view of a foldableplastic blank alternative embodiment having a static-dissipativelaminate and a flexible hinge laminate;

FIG. 13 is a perspective view with portions removed of the blank of FIG.8 folded up and assembled with a cover to make a rigid, rain-tightstructure;

FIG. 14 is a perspective view of a partially folded structure mounted toa wall for use as an electrical junction box;

FIG. 15 is a perspective view of the completely folded up structure ofFIG. 14 after assembly and attachment of the cover to the flanges;

FIG. 16 is a perspective view with portions removed of a structuresimilar to the structure of FIG. 13, showing that it is interlocked atthe corners of the sidewalls, does not have any flanges, and the coverprojects down over the interlocking means;

FIG. 17 is a top plan view of a blank for a wireway;

FIG. 18 is a perspective of two wireways of FIG. 17 folded up with theends bolted together and wires in the wireway;

FIG. 19 is a top plan view of a foldable plastic blank for making anenclosure for shipping printed circuit boards or the like;

FIG. 20 is a top plan view of the blank of FIG. 19, folded up withprinted circuit boards disposed therein;

FIG. 21 is a top plan view of a foldable plastic blank;

FIG. 22 is an enlarged, fragmentary, cross-sectional view along the line22--22 of FIG. 21;

FIG. 23 is an enlarged, fragmentary, cross-sectional view along the line23--23 of FIG. 21;

FIG. 24 is an enlarged, fragmentary, cross-sectional view along the line24--24 of FIG. 21;

FIG. 25 is an enlarged, fragmentary, cross-sectional view along the line25--25 of FIG. 21;

FIG. 26 is an enlarged, fragmentary, cross-sectional view along the line26--26 of FIG. 21;

FIG. 27 is an enlarged, fragmentary, cross-sectional view along the line27--27 of FIG. 21;

FIG. 28 is a top plan view of a foldable plastic blank;

FIG. 29 is an enlarged, fragmentary, cross-sectional view along the line29--29 of FIG. 28;

FIG. 30 is an enlarged, fragmentary, cross-sectional view along the line30--30 of FIG. 28;

FIG. 31 is an enlarged, fragmentary, cross-sectional view along the line31--31 of FIG. 28;

FIG. 32 is an enlarged, fragmentary, cross-sectional view along the line32--32 of FIG. 28;

FIG. 33 is an enlarged, fragmentary, cross-sectional view along the line33--33 of FIG. 28;

FIG. 34 is an enlarged, fragmentary, cross-sectional view along the line34--34 of FIG. 28;

FIG. 35 is a top plan view of a foldable plastic blank;

FIG. 36 is an enlarged, fragmentary, cross-sectional view along the line36--36 of FIG. 35;

FIG. 37 is an enlarged, fragmentary, cross-sectional view along the line37--37 of FIG. 35;

FIG. 38 is a perspective view of a folded blank;

FIG. 39 is a perspective view of a folded blank;

FIG. 40 is a perspective view of an enclosure formed from folded blanks;

FIG. 41 is a perspective view of a folded blank;

FIG. 42 is a perspective view of an enclosure formed from folded blanks;and

FIG. 43 is a block diagram of a control system for producing blanks.

DETAILED DESCRIPTION OF THE INVENTION

An extruded or calendared sheet of rigid plastic 5 is cut and/or routedto produce a flat, unitary, foldable blank 10, as shown in FIG. 3. Thisis done on a computer-numeric-controlled router machine, such as shownand described in U.S. Pat. No. 4,723,766. By inputting different datainto the computer and programming the machine, foldable blanks ofdifferent sizes can be automatically produced, all on the same machine.Custom sizes can be easily made by slight changes in the programming.

Manufacture of the blank 10 is done in at least three steps, with atleast three different tools. A blank 6 (FIG. 1) is first cut out of asheet of plastic 5 with a perimeter router 41 as shown in FIG. 5. Theperimeter router 41 rotates about a vertical axis 43. The router 41 cutsall of the way through the plastic sheet 5 and cuts out a shape which issubstantially octagonal as shown in FIG. 1. The corner portions 49 maybe cut out at this step or in subsequent steps. Grooves 15, 17, 19, 21,23, 25, 27, and 29 are then cut into the blank with one or more sawblades 45, as shown in FIG. 6. The saw blade 45 rotates about ahorizontal axis 47. The saw blade is made up of a number of separateteeth with the cross section shown in FIG. 6. Blank 8 (FIG. 2) resultsfrom this saw operation. Then, if the corner portions 49 were notinitially cut out in the first steps, a corner cutter (FIG. 7) cutsthrough the remaining thickness of the corner portions 49 from the blank8 at the bottom center of the grooves to make the foldable cross-shapedblank 10 of FIG. 3. Finally, holes (FIG. 3) are drilled in the blank asdesired. The computer numeric-controlled cutting machine (CNC machine)and noted tools are all well known in the art and have been for manyyears. Each separate tool is mounted on a separate head. The heads moveup and down on a Z axis and horizontally on a Y axis, and the bedholding the plastic sheet moves horizontally on an X axis in twodirections. The plastic sheet or blank is held in position on the bed byvacuum.

The cross-shaped foldable blank 10 has a rectangular backplate 12 andfour rectangular sidewalls 14, 16, 18, and 20 extending from each sideof the backplate. Each side wall has a length equal to that of the sideof the backplate 12 to which it adjoins. All four sidewalls have thesame width, which is equal to the desired depth of an assembledenclosure. Extending from each sidewall along the side opposite from thebackplate 12 are flanges 22, 24, 26, and 28, Each flange has a generallyisosceles trapezoidal shape with a base equal in length to that of theadjoining sidewall and with acute side angles of 45 degrees. Flanges 22and 26, which extend from opposite sidewalls 14 and 18, have foot-likeprojections 30 extending from each of its non-parallel sides. Theremaining flanges 24 and 28 have matching foot-like slots 32 cut intotheir non-parallel sides. The slots 32 are sized and shaped to snuglyreceive the matching projections 30, as shown in FIG. 11, thus providingresilient mechanical interlocking means for closing and stabilizing theassembled enclosure. Except for the interlocking means, the portions ofthe edges of the flanges which do come together do so at a 45-degreeangle. The projections and/or the slots, and, in fact, most or all ofthe exposed edges, may be at least partially beveled or rounded forsafety and to permit easier interlocking and assembly and disassembly.

Obviously, other mechanical interlocking means may be used in place ofthe slot and projection arrangement shown, such as sawtooth-shaped andkeystone-shaped projections and correspondingly shaped openings. Themechanical interlocking means is preferably integral with and hinged tothe top edges of the sidewalls opposite from the sidewall hinges to thebackplate. While a continuous flange as shown is believed to bepreferable, tabs integrally hinged to the edges of the sidewalls may beemployed, or the interlocking means may be integrally hinged to theedges of the sidewalls, as will hereinafter be shown and described.

Any means which holds the edges of the flanges together so that a rigidenclosure structure is formed achieves the purposes of this invention.For example, the edges of the flanges can be cemented together with glueor the inside edges of the sidewalls can be welded together with plasticwelding material.

Along the boundaries between the backplate and the four sidewalls, andbetween the sidewalls and each of the flanges, are a first set ofparallel grooves 17 and 25 and 21 and 29, and a second set of parallelgrooves 19 and 27 and 15 and 23 which are perpendicular to the first setof grooves. Each groove has a cross section as shown in FIG. 8, and ispredominantly V-shaped with inside walls or faces 36 and 38 which slopedownwardly from the top surface 37 of the plastic blank 10 at a45-degree angle to the bottom surface 39 to form a 90-degree includedangle between the groove walls. One inside wall 38 of each groove has asmaller 90-degree L-shaped furrow or groove 40 having two inside faces42 and 44 which are, respectively, parallel and perpendicular to theplane of the plastic blank. The other inside wall 36 of each furrow hasa step-like ridge or rib or tongue 46 with faces 48 and 50 which arealso respectively parallel and perpendicular to the plane of the plasticblank. As shown in FIG. 9, these ridges and furrows and complementaryand interfit to provide multiple contact surfaces in the folded positionwhich improve the structural stability of the enclosure. Multiplefurrows and conforming ridges and differently shaped furrows and ridgesor interfitting tongue-and-groove formations are possible to provide thesame structural stability or enhance it. These furrow and ridge featurescause the abutting sidewalls with beveled edges to interlock when foldedinto a box shape, preventing the possibility of adjoining beveled edgesfrom movement. The ridges and furrows also provide for an interferencefit for solvent welding where permanence is required. Furthermore, thefurrows may contain O-rings or other sealant material. In cross section,the ridge or male portion may have an enlarged head so that it has to beforced or popped into the furrow or female portion.

The included angle for the grooves should be 90 degrees so that when thesidewalls are folded up, they make a 90-degree angle with the backplateor are perpendicular to it and fit together for rigidity and support.The angle has to be cut out of the plastic sheet with a saw blade orotherwise formed in order to achieve the desired tolerances, whichshould be within 1 or 2 degrees at the most.

The saw blade 45 which cuts the "V" grooves continues to cut across thesides of the blank to leave corner portions 49 as shown in FIG. 2. Whenthe corner portions 49 are removed or cut out, in effect, one-half ofthe groove is removed so that the edge of one sidewall when folded upcan interfit with the edge of the other sidewall. Thus, the step-likeridge 46 of groove 19 is on the sidewall 18 (FIG. 9). The step-likeridge 46 of groove 15 is on the sidewall 14. For grooves 17 and 21, thestep-like ridge 46 is on the backplate 12. On backplate 12, grooves 15and 19 have furrows 40 and grooves 17 and 21 have ridges 46. Thus, oneset of parallel grooves on the backplate has ridges and the other sethas furrows and the cross-sections of the sets at right angles to eachother are reversed so that when the adjoining sidewall edges 18 and 20are abutted as in FIG. 10, they interfit and are water resistant.

The preferable ridge and furrow design has a 90% included angle as shownand is centered on the faces of the grooves. The ridges and groovespreferably have planar surfaces because they are easier to cut ormachine out as compared to rounded nonplanar surfaces.

As shown in FIG. 10, the sidewall edges 52 and 54 (FIG. 3) are beveledat a 45-degree angle and come together to make a 90-degree angle corner.In order for the edges of the sidewalls to interfit as shown in FIG. 10,the grooves have to be cut out of the blank in the reversed mannerdescribed above and the corner portions have to be removed so as toprovide interfitting, complementary sidewall edge surfaces.

One saw blade should be used to cut grooves 15, 17, 19 and 21 in orderto make them identical. If different blades are used, they may besharpened differently and the edges of the sidewalls may not interfit asaccurately as desired and they may not be water resistant. When a singlesaw is used to cut the grooves, it should be rotated 90 or 270 degreeturns about its vertical axis in order to have the grooves at rightangles to each other reversed in cross-section or mirror imagecounterparts. Alternatively, the work table can be turned 90 or 270degrees for successive grooves. In FIG. 8, groove 19 is reversed incross-section to groove 27 but otherwise identical.

It is contemplated that the included angle of the grooves can be greateror less than 90 degrees in order to provide other than right-anglestructures.

When adjacent sidewalls are bent upward 90 degrees, the beveled edgescome together and engage one another, with the ridge 46 of one edgeinterfitting with furrow 40 of the other edge to provide a type oftongue-and-groove configuration which resists slippage and providesadditional structural stability to the assembled enclosure. The multiplecontact surfaces also provide a water-resistant barrier. Waterresistance and structural stability can be further enhanced by providingmultiple grooves and conforming ridges at beveled edges to increase thenumber of contacting surfaces at each corner formed by intersectingsidewalls.

The corner joints of the sidewalls must be sufficiently water-resistantso as to prevent water infiltration when the enclosure is sprayed with ahose. Electrical component enclosures have to meet National ElectricalManufacturers Association (NEMA) specifications 1, 3, 3R, 3S, 4, 4X, 12,and 13, and Underwriters Laboratories specifications UL 50, 508, and764C. It has been found that the edges between sidewalls of enclosuresof the present invention can resist both water sprayed from a hose andwater under mild pressure. An enclosure of the present invention wastested by folding it up without the use of gaskets or seals, and fillingit with water. It did not leak.

As the size of the enclosure increases and the relative thickness of theplastic sheet material decreases, the enclosure may lose some of itsrain-tight integrity. In such cases, the edges may be solvent-weldedtogether.

Because the hinge 62 covers the joints between the sidewalls and thebackplate (FIG. 9), water cannot infiltrate. For water tightness, theimportant joint is thus at the corners of the sidewalls, as shown inFIG. 10. If that joint is simply two flat surfaces at 45-degree anglesto each other, there is water infiltration.

The foldable flat blank 10 has two intersecting grooves 19 and 21 (FIG.3) with two longitudinal axes. Upon folding up the sides 18 and 20perpendicular to each other and perpendicular to the backplate 12, thereare three intersecting longitudinal axes which form a corner or aninverted pyramid. Each groove has eight planar surfaces. When the blankis folded up, there are thus a total of twenty four planar surfaceswhich have to interfit at the corner.

Upon assembly, the foldable blank 10 (FIG. 3) forms five sides of anopen-faced, box-shaped structure, with the open side having a flangedrim. This is shown in FIG. 13. The box is easily assembled by foldingtwo opposite sidewalls 16 and 20 upward into a vertical positionrelative to the backplate. While maintaining the two sidewalls in thisvertical position, flanges 24 and 28 are folded 90 degrees toward theinside of the enclosure. Adjacent sidewalls 14 and 18 are then foldedupward into a vertical position relative to the backplate. The furrowsand ridges on sidewalls 14 and 18 then interlock with the furrows andridges in sidewalls 16 and 20. The foot-like projections 30 on sidewalls14 and 18 are then interlocked into the adjacent foot-like slots 32 onsidewalls 16 and 20. This is accomplished with a natural motion as theflanges 22 and 26 are folded into place.

As shown in FIG. 13, the interlocking means comprising the foot-likeprojection 30 which fit into the foot-like slots 32 lie in a planeparallel to the backplate, as do the flanges. The advantage of thisarrangement is that when the enclosure is assembled, the cover 56 coversor protects the interlocking means so that water cannot enter at thejoints of the interlocking means.

A cover or faceplate 56 (FIG. 4) is provided to complete the enclosure.The cover or faceplate 56 is made by cutting a sheet of plastic into arectangular shape having dimensions substantially identical to thebackplate and drilling screw holes 58 to match the holes in the flanges.The flanges are also provided with pre-drilled screw holes 51 which canbe brought into alignment with the holes 58 in the faceplate forattaching the faceplate to the assembled foldable structure viafasteners (not shown). It has been found that 1/4-inch screws with 20threads/inch are generally suitable for use with the invention, and thatscrew holes having a diameter of 0.170 inch are appropriate foraccommodating these 1/4-inch screws. Alternatively, the screw holes maybe drilled to a diameter of about 0.333 inch to receive a femalethreaded plastic insert for receiving 1/4-inch screws. The back of thefaceplate and/or the top of the flanges may be provided with a gasket,seal, or similar means to effect a seal therebetween. The holes 58 and51 may be drilled to a diameter of about 0.281 to receive aself-contained plastic speed fastener as is used in automotiveapplications.

In the preferred embodiment, the plastic blank has a 1/4-inch nominalthickness which corresponds to an actual thickness of about 0.239 inch.The distance from the point at which the faces of the V-shaped grooveintersect to the bottom face 39 of the plastic sheet along a lineperpendicular to the plane of the plastic sheet is typically between0.03 and 0.06 inch. This reduced thickness below the groove can providea flexible hinge 62 (FIG. 8) which allows the sidewalls to be easilybent 90 degrees upwardly into the groove and for the flanges to be bent90 degrees relative to the sidewall. The hinges or hinge portions 62thus become the fold lines for the plastic blank. The thickness of thehinge 62 varies with the flexibility of the plastic of the blank fromwhich the groove is cut. As can be seen in FIG. 8, the hinge 62 is muchthinner than the plastic blank. The grooves 27 and 19 are cut out of thetop surface 37 of the plastic blank to a depth which is close to thebottom surface 39, leaving the thin hinge 62 to function as the foldline. The plastic sheet has to be thick enough (usually not less than0.125 inch) to permit the formation of "V" grooves with ridges 46 whichcan interfit with furrows 40 as noted.

With some materials and in some situations, the hinge 62 may have to beheated before it is bent. The plastic may not be flexible enough topermit the hinge to be bent without the application of heat.

Almost any rigid or semirigid plastic material may be used in theproduction of the described enclosures. Materials used for constructingthe invention should be non-corrosive and should have a very lowelectrical conductivity. Preferred materials include solid or foamedpolyvinyl chloride, polyethylene, low density or high densitypolypropylene, acrylics, and polycarbonate. Polyvinyl chloride (PVC)materials suitable for use with the invention should have someplasticizer in them in order to provide a flexible or living hinge. If arigid PVC is used, without plasticizer, the hinge portions will have tobe heated before being bent. The polyether and polypropylene plasticmaterials do not require a plasticizer. PVC materials include thefollowing: VYNTEC, which is a PVC sheet manufactured by Vycom, ofScranton, Pennsylvania, and sold by Commercial Plastics and SupplyCompany, Cleveland, Ohio, and by Curbell Industrial Plastics Company,Cleveland, Ohio. PVC sheet plastics are also available from B.F.Goodrich Company, Cleveland, Ohio. Other suitable materials areTROVICEL, a foamed PVC manufactured by Huls America Inc., Piscataway,N.J. and sold by Commercial Plastics and Curbell; and SINTRA, anotherfoamed PVC which is manufactured by Alucobond Technologies Inc., Benton,Kentucky and is also available from either Commercial Plastics orCurbell. Other suitable materials for constructing the enclosure includethe following: acrylonitrile butadiene styrene; LEXAN or NORYL, eachmanufactured by the General Electric Company, Pittsfield, Mass., andeach available from Westlake Plastics Inc., Westlake, Ohio; KYDEX, ahigh impact, high temperature-resistant acrylic/PVC blend which can beobtained from either Commercial Plastics or Curbell; ELASTOGEN, aparticularly flexible PVC which can be obtained from GenCorp PolymerProducts Company, Newcomerstown, Ohio; and BOLTARON a high impact, hightemperature-resistant, conductive PVC composite which may also beobtained from GenCorp.

Solid PVC flexible hinges can frequently withstand 30 to 40 flexeswithout impairing the functionality of the hinges, while a foamed PVChinge can frequently withstand 8 to 10 flexes. Thus, the hinges can berepeatedly folded without fracturing or splitting.

Self-extinguishing polyvinyl chloride and flame retardant polypropylenematerial can be used for enclosures which are to be installed atlocations where fire hazards are present. Polyvinyl chloride is anacceptable material in the National Electrical Code. Such materials maybe comprised of homopolymers, copolymers or various blends thereof; theymay contain additives including colorants, plasticizers, heatstabilizers, extenders, impact modifiers, fillers, and inhibitorsagainst degradation due to oxidation, ultraviolet light, and the like.Enclosures can be provided in a variety of colors for color codingschemes for circuit identification such as fire alarms, communications,and electrical circuitry for aesthetic purposes. The enclosure, and inparticular the faceplate, may be made from transparent or clearpolymeric material when it is desired to view the contents of theenclosure without having to open the enclosure. A transparent or clearfaceplate and/or enclosure may be particularly desirable when meters,counters, or dials are contained within the enclosure. Transparentpolycarbonates or acrylics, such as Lucite, which can be obtained fromeither Commercial Plastics and Supply Company or from Curbell IndustrialPlastics Company, both in Cleveland, Ohio, are suitable materials foruse with the invention. Super abrasion-resistant LUCITE, which isresistant to scratching in abrasive environments, is also suitable.

While the rigid plastic enclosures described herein may be suitable fora variety of uses, they are particularly useful for enclosing electricalcomponents and instrumentation. Such applications include use of theenclosure as a pull box, a junction box, a pushbutton control box, anequipment cabinet, or as a splice box. Enclosures can be provided in avariety of sizes, and could include rectangular openings in oppositeside walls to form a wireway, or, in adjacent sidewalls to form awireway fitting. The enclosures may be shipped either flat orpreassembled, although it is far preferable to ship them flat. Suppliersand end-users should benefit from the space savings realized when thefoldable structures and faceplates are stored flat in stacks.

While the present invention contemplates the manufacture of flat sheetsof plastic which are stored or shipped in the flat condition and thenfolded together to make an enclosure, it also comprehends themanufacture of flat sheets which are folded together into enclosures atthe factory. The latter option still has substantial advantages overexisting prior art enclosures. To begin with, a single CNC machine canproduce a broad product line of enclosures. Other non-metallic enclosuremanufacturers require a different mold for each configuration as well asa different mold for each type of plastic material. Molds are expensiveand require costly injection molding machinery of varying sizes. Thecapital outlay for the molded enclosures requires high levels ofinventory to justify long production runs. The present invention permitslow capital cost and great manufacturing flexibility.

FIG. 14 illustrates a typical use of the invention as an electricalenclosure, and demonstrates some of the advantages of the invention. Theenclosure can be mounted to a wall with screws via screw holes drilledinto the backplate of the enclosure or by using mounting brackets 60, asshown in FIGS. 14 and 15. The brackets can be cemented to the top andbottom sidewalls or affixed by commonly known mechanical means such asinterlocking slots and knobs or screws. It is preferable, as illustratedin FIG. 14, to affix the enclosure to the wall, with the top sidewallfolded down as illustrated, pull wire or cable through the top sidewall,and work with the other three sidewalls open, partially open, or atleast non-interlocked. Typically, an electrician would drill one or moreholes in the top or other sidewalls and affix conduit 74 thereto,generally utilizing sealing means to make the connection between theconduit and the hole water-resistant or watertight. Thereafter, cable orwire 76 is pulled through the conduit into the interior of theenclosure. The electrician then could mount necessary or desiredcomponents in the enclosure. Such components could include meters,instrumentation, counters, fuses, circuit boards, or other electrical orelectronic devices or components. The electrician will generally thenmake any required, necessary or desirable electrical connections orwiring, etc. The electrician can then fold the sidewalls of the plasticsheet to close up the enclosure and lock it into its assembled or closedposition.

By bending the sidewalls towards or flat against the wall to which thefoldable structure is mounted, an end user, such as an electrician, isfree to work in the box unimpeded by the sidewalls. This ability to workunrestricted by the sidewalls should enable the end user to work morequickly and to possibly use a smaller enclosure for a specificapplication. Similarly, subsequent repairs are more easily made byunfolding the enclosure to move the sidewalls out of the way, performingthe repair, and refolding the enclosure.

Fixed sidewalls in conventional enclosures make wire pulling difficult,as the wire must be bent to go over the fixed side opposite the fittingas it enters or exits the termination fitting on the conduit. This is anarea where the cable insulation can be stripped as it rides over theedge of the fitting. Many conventional enclosures are oversized tominimize the cable stripping problem. Having the sides open on the newdesign allows downsizing of the enclosure.

Commonly used steel enclosures are generally provided with knockoutholes for running conduit to the enclosure. These knockout holes areused because of the time and difficulty involved in drilling holes intosteel on site. The plastic enclosures provided by the present inventiondo not require knockout holes, since holes can be quickly and easilydrilled into the plastic on site. The end user is therefore not confinedto preselected knockout holes but, to the contrary, is able to drillholes of any size where they are desired. As shown in FIG. 14, thesidewalls of the enclosure fold to a position so that they areperpendicular to the wall to which the enclosure is mounted, whichpermits a multitude of enclosures to be mounted, with the sidewall ofone enclosure abutting the sidewall of the next. Holes can be drilledthrough the abutting walls in a single drilling operation to permitcommunication between adjacent enclosures. This ability to connectenclosures to one another in a side-by-side fashion with abuttingsidewalls in parallel relationship facilitates enclosure of large orcomplicated electrical systems which cannot be housed in a singleenclosure. This is called "ganging," and is not possible withinjection-molded enclosures.

Computer-numeric-controlled (CNC) cutting machines are sold, forinstance, by Motion Master Corporation, of Vista, Calif., and ShinkoTrading Co. Ltd., of Japan. Custom designed circular saw blades androuters can be obtained from Herco Inc., Newcomerstown, Ohio.

While it is believed that the folded and mechanically interlockedenclosure described above provides a suitable enclosure for mostelectrical equipment applications, it is also recognized that anenclosure having heavy duty, watertight seams at the intersecting edgesof sidewalls may be desirable in certain situations. The modifiedenclosure is made by adding two additional steps to the previouslydescribed manufacturing methods. First, one beveled edge of the sidewallis routed or otherwise grooved to produce a larger furrow or groovehaving a semicircular cross section in the face of the sidewall. Second,the semicircular groove is filled with a bead of gasketing materialwhich, upon setting, bonds to the plastic or is mechanically held inplace by such means including an undercut or an overhang and has anapproximately circular cross-sectional shape which provides a permanent,reusable gasket that remains attached to the semicircular grooves. Thestep-like projection compresses the gasket to form a seal at the cornerof the projection when the edges are folded up against one another.Suitable gasketing materials include silicone and neoprene.

Alternatively, sealant may simply be disposed in the furrows 40. Whilesealants and gaskets may be employed, they are not required. Theadvantage of the present invention is that the enclosure is rain-tightwithout the need for gaskets or sealants. The sealant may be appliedwith the CNC machine.

To provide additional rain-tightness or water-resistance, the face ofthe flanges 22, 24, 26, and 28 and/or the inner side of the faceplatemay be provided with grooves. The grooves are made with a speciallyshaped routing bit which provides a semicircular groove having aninverted V-shaped projection extending from the bottom of the groove.The faceplate may have a semicircular groove filled with a bead ofpourable gasket material, such as silicone or neoprene, which forms acircular cross-section and bonds to the groove or engages in aninterference fit to form a permanent reusable gasket. When the faceplateis fastened onto the assembled structure 10, the corner or tip of theprojection compresses the gasket to form a watertight seal. Anotheralternative method of sealing the faceplate to the enclosure is to use apreformed spongy neoprene gasket having a pressure-sensitive adhesiveprotected by a releasable paper. This type of gasket can be shipped withthe enclosure, in a separate or attached package, ready for installationby the user.

In accordance with an alternative embodiment of the invention, stainlesssteel or other suitable metal or plastic hardware can be provided forsecuring the faceplate to the foldable structure of the plasticenclosure. Commonly known hinges and latches can be used in lieu ofscrews for fastening the faceplate to the foldable structure, therebyfacilitating easy access into the enclosure where repeated access isanticipated. Hinges and latches can be either screwed to the faceplateand sidewalls or, in the case of plastic hardware, cemented, glued, orultrasonic-welded thereto.

An alternative structure is shown in FIG. 16 in which there are noflanges hinged to the sidewalls and the edges of the sides are heldtogether with an interlocking means comprising a tongue 84 on sidewall82 and a groove 85 in sidewall 83. The cover 80 has edge portions 81which project downwardly over the interlocking means. The enclosure ofFIG. 16 is not watertight unless solvent-welded.

FIGS. 17 and 18 concern what are called "wireways." These are open,elongated structures into which wires are laid, as shown in FIG. 18.FIG. 17 is a plan view of a wireway blank 90. The blank 90 is long andnarrow with sidewalls 93 and 94, flanges 91 and 92, a backplate 95, andnarrow side or end walls 96 and 97. The central sections 98 and 99 ofthe end walls are relieved or open. The means for locking the structuretogether comprise tongues 88 on the end walls which fit into grooves 89in the flanges.

FIG. 18 shows two wireways 71 and 73 assembled and bolted together.Holes 87 in blank 90 are the bolt holes. The wireways are otherwise thesame as the enclosures previously shown and described herein. Anindividual wireway may be fabricated with closed ends and is called a"trough."

As used in the specification and claims herein, an open-faced,box-shaped structure means a five or six-sided box with one of the sidesor faces being open or partially open, or providing access to theinterior of the box, or being openable to provide access to the interiorof the box. Typically, the box-shaped structure can be described as aright parallelepiped, with each face or side or base (whether open orclosed) being or defining a rectangle. Except for wireways, mostenclosures are square. It is contemplated, however, that pentagon orhexagon or other less conventionally shaped structures may be made inaccordance with my invention.

FIGS. 19 and 20 show how enclosures of the present invention can be usedas shipping containers for printed circuit boards. A blank 11 (FIG. 19),which is the same as blank 10 of FIG. 1, is provided with slots 33 cutin the backplate 12' and notches 31 cut into the outside edges of theflanges 22 and 26. The slots 33 are parallel to opposite grooves 17 and21 of the blank and the notches 31 are cut into the flanges at the endsof the slots so that when the blank is folded up to make a structure,the notches 31 and slots 33 match up and printed circuit boards 34 canbe disposed into the structure and suitably supported as shown in FIG.20. FIG. 20 is a top plan view of the structure folded up from the blank11 of FIG. 19, with the circuit boards 34 therein. A cover 56 just likethe cover of FIG. 4 is placed over the structure to complete theenclosure.

An enclosure with the printed circuit boards in it is shipped to thecustomer. Upon receipt of the enclosure, the customer opens it up andremoves the printed circuit boards. The enclosure is then disassembledand opened to a flat blank like that shown in FIG. 19. The blank andcover are then shipped back to the manufacturer for re-use.

An enclosure such as described above can be used to ship magnetic tapesor discs, printed circuit boards, electronic controls or circuitry, orother goods requiring special noise-free protection or handling. Theenclosure can hold the circuit boards or other goods in place duringstorage, and while they are at a work station or processing point.

The above goods have to be protected from electromagnetic interference(EMI), electrostatic discharge (ESD), and radio frequency interference(RFI). For these applications, static-dissipative and/or electricallyconductive additives can be added to the polymer blend to protect thecircuitry being enclosed. Suitable static-dissipative additives arecarbon black and stainless steel chips. It has been found that adequatestatic-dissipative characteristics are achieved without adverselyaffecting the desired properties of the enclosure when the polymer blendcontains from about 0.1 to about 1.9% by weight of static-dissipativeadditives.

Referring to FIG. 12, in accordance with another aspect of theinvention, static-dissipative characteristics and shielding forelectromagnetic and radio frequency interference are provided by alaminate of static-dissipative material 64 which is applied to eitherthe interior or exterior surfaces of the enclosure components includingboth the foldable structure and the faceplate. A thin layer ofstatic-dissipative material, such as MITECH, which is available fromMitech Corporation, Twinsburg, Ohio, STATRITE, which is sold by B.F.Goodrich Company, Cleveland, Ohio, or ELECTRAFIL, which is sold by AkzoEngineering Plastics, Inc., Evansville, Ind., is bonded to the surfacesof the enclosure using a lamination glue or polymer solvent such astetrahydrofuran or methylethyl ketone-based solvents or heat. The exactthickness of the laminate is less important provided that a completecovering of the internal surfaces of the enclosure is achieved; however,because static-dissipative materials are relatively expensive, thethickness of the laminate should be kept to a practical minimumconsistent with economical manufacturing techniques. Astatic-dissipative laminate of a material such as MITECH having athickness from about 0.015 to about 0.035 inch has been found to beadequate.

FIG. 12 shows a cross-sectional view of a preferred embodiment whereinthe plastic sheet is comprised of three separate layers. A central layer66 is made from a hard, rigid, durable material, preferably foamed orsolid polyvinyl chloride, and it has two thin outer layers laminated toit. On the outside face, a thin layer 68 of highly flexible plastic,such as polypropylene, polyethylene, or plasticized polyvinyl chloride,provides a flexible or living hinge 69 which can be bent back and forthbetween the open and closed positions a multitude of times withoutsplitting, cracking, or substantially deforming. The inside face of theplastic sheet has a static-dissipative layer 64, as previouslydiscussed. The static-dissipative layer 64 joins at right angles whenthe blank is folded together into an enclosure.

An enclosure may also be formed from two blanks. Referring to FIG. 21, afirst blank 100 is cut from a sheet of plastic using a CNC machine. Thefirst blank 100 has a planar surface. A saw blade or milling cuttersimilar to that of FIG. 6 makes passes in the direction A along the line102 and the line 104, in the direction B along the line 106 and the line108, in the direction C along the line 110, and in the direction D alongthe line 112. The saw blade does not cut all of the way through thefirst blank 100, a small thickness of the plastic sheet remains at thelines 102, 104, 106, 108, 110, 112. A router similar to that of FIG. 5is used to trim the first blank 100 from the plastic sheet making squareedges at the lines 102, 108, 110, 112. A first edge of the first blankis thus provided at the line 102, and a second edge provided at the line108.

Similarly, a second blank 114 (FIG. 28) is cut from the same sheet ofplastic, or another sheet of plastic using a CNC machine. The secondblank 114 has a planar surface. A saw blade similar to that of FIG. 6makes passes in the direction E along the line 116 and the line 118, inthe direction F along the line 120 and the line 122, in the direction Galong the line 124, and in the direction H along the line 126. The sawblade does not cut all of the way through the second blank 114, a smallthickness of the plastic sheet remains at the lines 116, 118, 120, 122,124, 126. A router similar to that of FIG. 5 is used to trim the secondblank 114 from the plastic sheet making square edges at the lines 116,122, 124, 126. A first edge of the second blank is thus provided at theline 116, and a second edge provided at the line 122. In addition, anopening 128 may be cut in the second blank 114 with a router similar tothat of FIG. 5.

The line 104 is located a desired distance from the line 102 and theline 106 is located that same distance from the line 108. The line 118is also located that same distance from the line 116 and the line 120 islocated that same distance from the line 122.

The lines 102, 104, 106, 108 are parallel. The lines 116, 118, 120, 122are parallel. The lines 110, 112 are parallel and at right angles to thelines 102, 104, 106, 108. The lines 124, 126 are parallel and at rightangles to the lines 116, 118, 120, 122.

Exemplary cross sectional views of the surfaces of the blanks are shownin FIGS. 22-27 and 29-34. The grooves at the lines 104 and 106 of thefirst blank 100 and at the lines 118, 120 of the second line provide"live hinges." The blanks 100, 114 may be folded on these hinges to formthree-sided structures as shown in FIGS. 38 and 39. Depending on thetype plastic used and the thickness of the plastic at the fold lines, itmay be necessary to heat the plastic at the bottom of the grooves toprovide the necessary flexibility before folding.

The groove 130 about the line 104 (FIG. 23) is composed of the two walls132, 134 having an included angle of about 90 degrees. The wall 132includes a furrow 136 and the wall 134 includes a ridge 138. When thefirst blank 100 is folded on the line 104, the furrow 136 interfits withthe ridge 138. This interfitting engagement improves the strength andstability of the resulting structure and forces a square joint. Thefurrow 136 and the ridge 138 may be, for example, a right angledprotrusion and a right angled indentation, respectively.

Each of the grooves in the blanks 100, 114 have a similar structure,except that the relative positions of the ridges and furrows areoriented so that ridges will be aligned with furrows where sides of theresulting enclosure join.

When the blanks 100, 114 are cut from the plastic sheet along the lines102, 108, 110, 112 and the lines 116, 122, 124, 126, respectively,"half" of a groove remains as shown in FIGS. 22, 25, 26, 27, 29, and 32.Similar to the grooves above, these "half grooves" have ridges orfurrows that interfit furrows or ridges, respectively, where sides ofthe resulting enclosure join.

Referring to FIG. 38, when the first blank 100 is folded on the lines104, 106, a three-sided structure is formed having two parallel sides140, 142 perpendicular to a side 144 connecting the sides 140, 142

Referring to FIG. 39, when the second blank 114 is folded on the lines118, 120, a three-sided structure is formed having two parallel sides146, 148 perpendicular to a side 150 connecting the sides 146, 148. Theopening 128 is in the side 150 but could be located in any or all of thesides if desired.

To complete an enclosure, the edge 152 is joined to the edge 154, theedge 156 is joined to the edge 158, the edge 153 is joined to the edge155, and the edge 157 is joined to the edge 159 to form a box-likeenclosure 160. In addition, the edge 162 may be joined to the edge 164,the edge 166 may be joined to the edge 168, the edge 170 may be joinedto the edge 172 and the edge 174 may be joined to the edge 176. Theseedges each provide assembly surfaces and may be joined, for example, byplastic welding, heat or solvent fusing, or adhesive.

When the edges are joined, each edge contributes either a ridge orfurrow that interfits with the opposite edge. This occurs because thegrooves of the first blank 100 have a reversed cross section from thatof the second blank 114. In addition, intersecting grooves of each blankare cut with reversed cross sections.

Another enclosure made from two blanks may be provided with one or moreflanges or wings. These wings may be use, for example, for mounting theenclosure or mounting structures such as a door to the enclosure.Referring to FIG. 35, a first blank 100' is similar to the first blank100 (FIG. 21) except that wings 178, 180 extend from the central section182 of the blank 100'. The wings 178, 180 may be formed by the routercutting along the lines 110 and 112, detouring around the portion oflines 110, 112 adjacent to the central section 182.

Similar to the first blank 100, the first blank 100' can be folded intoa three-sided structure (FIG. 41). Assembly of the enclosure 160' (FIG.42) is similar to the enclosure 160 (FIG. 40) except that the edge 155is received in the groove 184 and the edge 159 is received in the groove186. The resulting enclosure 160' has wings 178, 180 extending from thebottom side 144'. The enclosures can have from zero to eight wings byleaving a desired number of portions of the plastic sheet extending fromthe periphery of the blanks.

The grooves 184, 186 can be cut more shallowly than the remainingportions of the corresponding groove in the first blank 100'. Thisprovides stronger wings. The edges 155, 159 would be trimmed anadditional amount corresponding to the reduction in groove depth. Theedges would be trimmed slightly closer by the router.

One advantage of the method shown in FIGS. 21-42 is that there is lessscrap. It has been found that more enclosures can be cut from a singlesheet of plastic than can be cut from a single sheet of plastic usingthe method of FIGS. 1-4.

Referring to FIG. 43, both methods can be quickly adapted to theproduction of different size enclosures while minimizing scrap materialby the use of a CAD-CAM program 202 and a layout optimizing program 204.An operator specifies the finished dimensions of a desired enclosure asan input to the CAD-CAM program 202. The CAD-CAM program 202 determinesthe dimensions and grooves required for the blanks for the enclosure, aswell as the necessary steps for the CNC machine 206 to perform. In itssimplest form, the optimizing program 204 displays the planned blanks ona virtual sheet of plastic on a display terminal. The operator thanmoves the planned blanks on the virtual sheet of plastic to minimizescrap. In a more complex form, the optimizing program 204 determines asolution that minimizes scrap without operator intervention.

The ability to use both methods with such automated techniques providesa substantial advantage in speed, flexibility and efficiency.

Another advantage of both methods is that holes can easily be drilledinto the flat plastic sheet at special desired locations to provide thecompleted enclosure with holes located exactly where the user wantsthem.

While the invention has been shown and described with respect to aparticular embodiment thereof, this is for the purpose of illustrationrather than limitation, and other variations and modifications of thespecific embodiment herein shown and described will be apparent to thoseskilled in the art all within the intended spirit and scope of theinvention. Accordingly, the patent is not to be limited in scope andeffect to the specific embodiment herein shown and described nor in anyother way that is inconsistent with the extent to which the progress inthe art has been advanced by the invention.

What is claimed is:
 1. A method for making and using a electricalcomponent enclosure, comprising:providing at least one sheet ofelectrically insulative high-impact water-resistant plastic materialwhich is suitable for use as a electrical component enclosure; cutting afirst blank from said sheet, said first blank having a planar surface, afirst edge, a second edge, a first assembly surface and a secondassembly surface, said first blank edges being parallel and equal inlength; cutting a first groove in said first blank planar surfaceparallel with said first blank edges and spaced a desired distance fromsaid first blank first edge; cutting a second groove in said first blankplanar surface parallel with said first blank edges and spaced saiddesired distance from said first blank second edge; cutting a secondblank from said sheet or another sheet, said second blank having aplanar surface, a first edge, a second edge, a first assembly surfaceand a second assembly surface, said second blank edges being paralleland equal in length; cutting a first groove in said second blank planarsurface parallel with said second blank edges and spaced said desireddistance from said second blank first edge; cutting a second groove insaid second blank planar surface parallel with said second blank edgesand spaced said desired distance from said second blank second edge;folding said first blank at said first blank first groove therebyforming a first side that includes said first blank first edge and twoside edges perpendicular to said first blank first groove; folding saidfirst blank at said first blank second groove thereby forming a secondside that includes said first blank second edge and two side edgesperpendicular to said first blank second groove, said first and secondsides being parallel to each other and perpendicular to a third sideformed from a remaining portion of said first blank connecting saidfirst and second sides; folding said second blank at said second blankfirst groove thereby forming a fourth side that includes said secondblank first edge and two side edges perpendicular to said second blankfirst groove; folding said second blank at said second blank secondgroove thereby forming a fifth side that includes said second blanksecond edge and two side edges perpendicular to said second blank secondgroove, said fourth and fifth sides being parallel to each other andperpendicular to a sixth side formed from a remaining portion of saidsecond blank connecting said fourth and fifth sides; attaching saidfirst blank first and second edges to said second blank first and secondassembly surfaces, respectively; attaching said second blank first andsecond edges to said first blank first and second assembly surfaces,respectively to form an electrical enclosure; and installing thecompleted enclosure in an electrical system and using the enclosure forelectrical components.
 2. A method according to claim 1, wherein atleast one of said assembly surfaces is a groove cut in said first blank,said groove mating with the respective edge of said second blank and aportion of said first blank extending outwardly from said mating.
 3. Amethod according to claim 1, wherein at least one of said assemblysurfaces is another edge of said first blank, said another edge matingwith the respective edge of said second blank.
 4. A method according toclaim 1, further comprising cutting an opening in at least one of saidsides.
 5. A method according to claim 1, wherein said grooves have anincluded angle between first and second groove walls of substantially 90degrees, the cross section of each groove defining at least one ridge ina first groove wall which interfits with a furrow in a second groovewall when said blanks are folded.
 6. A method according to claim 5,wherein said grooves of said first blank have an identical but reversedcross section of said grooves of said second blank and furthercomprising cutting said side edges to correspond to a single wall ofsaid grooves, said single wall being reversed in cross section from thatof the grooves of the respective blank, whereby respective side edges ofrespective blanks have interfitting ridges and furrows when said blanksare folded and attached.
 7. A method according to claim 1, wherein thecutting steps are performed on a computer-numeric-controlled routermachine and the cutting steps are put into the memory of the machine soas to be capable of consistent repetition.
 8. The method according toclaim 7, wherein the computer-numeric-controlled router machine isprogrammed by an operator inputting a plurality of desired finisheddimensions of said enclosure into a CAD-CAM program.